Suppressing wax in oils



NITED STATES T OFiE sorrnassmc wax in ores Charles Edwin Greensfelder,

Shell Development Com,

Francis Suh'o ea, Calif" era to San Francisco,

Calif., a corporation of Dela No Draf Application October 22, 1934,

Serial N0. 149,499

This invention relates to a process for suppressing or inhibiting theformation of solid wax in hydrocarbon oils.

Hydrocarbon oils 5 uents often lose their separation of particles ofrated wax appears either in the form of within the oil or as a more orless crystalline precipitatewhich may remain dispersed throughout theoil. Frequently, the separated wax will be found collecting on the wallsof an oil container, especially at the surface of the oil, or rising tothe oil surface. Such separation of wax may oclimpidity because of thesolid wax. This sepacur at temperatures which are substantially abovethe pour point or congealing temperature of the oil, with the resultthat small constrictions in a lubricating system may become obstructed.'The lack of clarity is also undesirable, because of the unattractiveappearance of the oil. This is manifested bothin the formation of cloudsor dispersed more or less crystalline precipitates or in the formationof surface wax.

It is one object of our invention to reduce, delay, or prevent theseparation of such particles of wax by the addition of certain innocuoussubstances to the oil, which are hereinafter referred to as waxsuppressors". Other objects of our inventionvwill be apparent from areading of this specification.

We have found-that the addition quantities of acids effects the desiredsuppression of wax. As used in the present specification and claims, weuse the term "saccharose as a generic term to include both monoandpoly-saccharoscs. Examplesz arabinose, lyxose, glucose, fructose, su-

crose, avocado sugar and cabbage sugar. The acyl radical shouldpreferably contain between ten and thirty-two carbon atoms and maycomprise either a straight or a branched chain, and be either saturatedor not. Examples: Palmitlc acid, stearlc acid, oleic aci yp ae c, acid.linoleic acid, and other aliphatic and particularly fatty acids. Thesaccharose should, preferably, contain between four and ten hvdrowradicals, either all or a part of which are then esterifled. We havefound that best resultsare achieved when more than three and not morethan ten hydroxy groups are esterifled.

Examples of saccharose esters are: tetraor pentastearyl dextrose(glucose d), tetraor pentastearyl laevulose (fructose d) pentacaprylsaccbarose, octabehenyl maltose. etc.

We have found tetraand octastearyl w 30 of very small which contain waxyconstita cloudy esters of saccharoses with aliphatic of about 40 F.

especially effective as wax suppressors, and it is to be understood thata preferred embodiment of our invention comprises the use of thesesubstances.

The eifective quantity quired for inhibiting wax hydrocarbon oils varieswith different suppressors and also depends upon the quantity and thenature of the wax in the oil. We have found that usually the effectiveamounts vary between 0.05% and 1.5% of the oil.

Such quantities of wax suppressors, as are used according to thisinvention, have no significant eifect upon the pour point of the oil,but have a marked efiect in preventing or retarding the separation of.wax. When used in excessive concentrations, the wax suppressors may ormay not exhibit pour point reducing properties. In general, we 'foundthat the property of inhibiting the formation of wax is not necessarilyaccompanied by the property of reducing pour points of wax-containingoils. Thus, a number of known pour point reducers were tried on severaloils, but failed to suppress the separation of wax at temperatures abovepour points of the oils.

The wax suppressors may be added to the oil either at ordinary or atelevated temperatures. If the oil being treated contains particles ofseparated solid wax, it is generally desirable to warm the oil todissolve the wax prior to its treatment.

A particular advantage of the use of the esters of our invention is thatthey do not appreciably darken the color of are of a light color, andare usedin quantities of the order of 1.5% or less, they usually causeno color change when used to suppress the formation of wax.

To illustrate the use and effect of our wax suppressors, the followingexamples are presented:

Example I Example 11' raflinate, when kept at temperatures becameobscured because of the formation of a dull waxy When-0.25%ofoctastearylwasadiiedtotheoilthis and the addition of of wax suppressorre- Asimilar formation in different theoil. Since most of them effectivealthough smaller amounts delayed the formation of this dull surface,although it did not entirely prevent it.

The addition of 1% of Paraflow (a condensa tion product of a waxyhydrocarbon material with an aromatic hydrocarbon), a known pour pointreducer, had no retarding efiect onth'is precipitation of wax.

Example III Example IV A Coalinga Edeleanu rafiinate showed turbidityand cloudiness after two days storage at F. The addition of 0.1% ofpentastearyl glucose to samples of the same raflinate caused them toremain clear for over days at 70 F.

Example V A Coalinga Edeleanu raflinate showed turbidity and cloudinessafter two days storage at 70 1 The addition of 0.1% of octastearylsaccharose to samples of the same rafiinate caused them to remain clearfor over days.

While these particular examples demonstrate the eflectiveness of stearicacid-glucose and of stearic acid-sucrose condensation products, ourinvention is not limited thereto, as other saturated and unsaturatedmonobasic aliphatic acids, having from ten to thirty-two carbon atoms,may be used.

Instead of the particular aldo-hexose and the dihexose, other keto oraldo monosaccharoses or polysaccharoses may be used.

As used in the present specification and claims, the expressionsuppression of wax means the prevention, reduction or retardation of theformation of solid wax in a body of 011.

Although we have heretofore disclosed that esters of monoandpoly-saccharoses are suitable for suppressing wax, we have found thatthe ester of monoand of di-saccharose is especially useful for thispurpose. A

We claim as our invention:

1. A limpid oil composition comprising a mineral oil containing wax inamount and composition normally to cause visible wax to separate fromthe oil in a solid state at temperatures above the pour point of thewax-containing oil, and a small quantity of pentastearyl glucose tosuppress the said separation of visible wax.

2. A Jimpid oil composition comprising a mineral oil containing wax inamount and composition normally to cause visible. wax to separate a

